Salience phenomena put an element from a linguistic or visual message forward ("pop-up" effect). By confronting works resulting from various research fields, and with the aim to apprehend salience as a general cognitive mechanism, we propose a classification of the factors that make an entity salient in a linguistic utterance or in a visual scene. The factors cover prosodic, lexical, syntactic, semantic, as well as pragmatic aspects. Therefore, salience covers several markers, several linguistic notions (e.g. notions from the information structure), and grows up as a multifaceted notion. With our classification, we emphasize the links between salience and topic, salience and focus, etc.